M05.A
Abnormal rheumatoid factor and anti-citrullinated protein antibody with rheumatoid arthritis
M05.A (also written M05A) is a billable ICD-10-CM diagnosis code for abnormal rheumatoid factor and anti-citrullinated protein antibody with rheumatoid arthritis. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 211 codes in category M05 (Rheumatoid arthritis with rheumatoid factor). The Alphabetic Index lists it under 1 entry. Its coding notes include a Code first instruction, 3 Excludes1 entries and 10 Excludes2 entries.
Code first
If the underlying condition listed here is present and known, sequence it first.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (10 notes)
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Notes
Also from chapter/block level (1 note)
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 1 entry